I was reading my Episode 3 visual dictionary when i found that crab droids can be surveillance drones at 1 meter - or trailblazers at 6 meters! So i made a 6 meter crab droid at minifig scale. It turned out pretty well if i may say so myself and the only problem it the fact that its front legs are a bit to heavy. If you have any comments on improvements then feel free to comment and rate.